In citing data from an online database, include the following elements, if applicable, in the order shown:
Author(s). Title of the database [database online]. Publisher’s location (city, state, or, for Canada, city, province, country, or, all others, city, country): publisher’s name; year of publication and/or last update. URL [provide URL and verify that the link still works as close as possible to publication]. Accessed [date].
Additional notes that might be helpful or of interest to the reader (eg, date the site was updated or modified) may also be included.
1. PDQ: NCI’s Comprehensive Cancer Database. Bethesda, MD: National Cancer Institute; 1996. http://www.cancer.gov/cancerinfo/pdq/cancerdatabase. Updated December 18, 2001. Accessed April 29, 2004.
2. Genew, HUGO Gene Nomenclature Committee (HGNC). Human Gene Nomenclature Database Search Engine. http://www.gene.ucl.ac.uk/cgi-bin/nomenclature/searchgenes.pl. Accessed February 27, 2004.
3. Online Mendelian Inheritance in Man, OMIM. Baltimore, MD: Johns Hopkins University Press; 2000. http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=OMIM. Accessed December 6, 2005.